Inhibiting the growth of microorganisms in vitro


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A discussion on the inhibiting the growth of microorganisms in vitro. Different processes of sterilization and disinfection.

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Inhibiting the growth of microorganisms in vitro

  1. 1. Sterilization  Is the complete destruction of all microorganisms, including cells, spores, and viruses. When something is sterile, it is devoid of microbial life. Sterilization of objects can be accomplished by dry heat, autoclaving, gas, various chemicals and certain types of radiation.
  2. 2. Disinfection  Is the destruction or removal of pathogens from nonliving objects by physical or chemical methods. Pasteurization is a method of disinfecting liquids.  Disinfectants-are chemical agents used to eliminate pathogens  Antiseptics are solutions to disinfect skin and other living tissues.  Sanitation-is the reduction of microbial populations to levels considered safe by public health standards.
  3. 3. Microbicidal agents  Microbicidal agents-are disinfectants to kill microbes  Bactericidal agents are disinfectants that kill bacteria but not necessarily bacterial endospores  Sporicidal agents- to kill bacterial endospores  Algicidal agents-are used to kill algai in swimming pools and hot tubs.  Viricidal agents to destroy viruses  Pseudomonicidal agents kill pseudomonas species  Tuberculocidal agents- kill M.tuberculosis
  4. 4. Microbistatic agent  Is a drug or chemical that inhibit the growth and reproduction of microorganisms.  A bacteriostatic agent is one that specifically inhibits the metabolism and reproduction of bacteria.
  5. 5.  Sepsis-refers to the presence of pathogens in blood or tissues  Asepsis means the absence of pathogens  Antisepsis-is the prevention of infection  Antiseptic technique- developed by Joseph Lister in 1867,refers to the use of antiseptics.  Sterile technique-is practice to exclude all microorganisms from a particular area, so that the area will be sterile.
  6. 6. Using physical methods to inhibit microbial growth  The physical methods commonly used in hospitals, clinics and laboratories include heat, the combination of heat and pressure, desiccation, radiation, sonic disruption, and filtration.
  7. 7. Heat  Is the most practical, efficient and inexpensive method of sterilization of those inanimate objects and materials that can withstand high temperatures  2 factors: A. Temperature B. Time -determine the effectiveness of heat for sterilization
  8. 8.  There is a considerable variation fro organism to organism in their susceptibility to heat; pathogens usually are more susceptible than nonpathogens .
  9. 9. Dry Heat  Dry heat baking in a thermostatically controlled oven provides effective sterilization of metals, glasswares, some powders, oils and waxes.
  10. 10. Moist heat  Heat applied in the presence of moisture , as in boiling or steaming, is faster and more effective than dry heat and can be accomplished at a lower temperature; thus it is less destructive to many materials that would damaged at higher temperatures.
  11. 11. Cold  Refrigeration merely slows the growth of most microorganisms; it does not completely inhibit the growth.
  12. 12. Desiccation  The process of being thoroughly dried
  13. 13. Radiation  The UV rays, which do not penetrate glass and building materials, are effective only on surfaces. They penetrate cells and thus can damage DNA .
  14. 14. Filtration  Filters of various pore sizes are used to filter or separate cells, large viruses, bacteria and certain other microorganisms from the liquids or gases in which they are suspended.
  15. 15. Gaseous atmosphere  It is possible to inhibit growth of microorganisms by altering the atmosphere in which they are located
  16. 16. Using chemical agents to inhibit microbial growth  Chemical disinfection refers to the use of chemical agents to inhibit the growth of pathogens, either temporarily or permanently.
  17. 17. Various factors affect the efficiency or effectiveness of a disinfectant  Prior cleaning of the object or surface to be disinfected  The organic load that is present, meaning the presence of organic matter on the materials being treated  The bioburden, meaning the type and level of microbial contamination  The concentration of the disinfectant  The contact time, meaning the amount of time that the disinfectant must remain in contact with the organisms in order to kill them. The physical nature of object being disinfected  Temperature and ph
  18. 18. Characteristics of an ideal chemical antimicrobial agent  It should kill a wide variety of microorganisms  It should be fast acting, contact time should be short  Should not be affected by the presence of organic material  Must be nontoxic to human tissues and noncorrosive and nondestructive to materials  It must be soluble in water and easy to apply  Should be inexpensive and easy to prepare  Should be odorless  It must be stable both as a concentrate and as a working dilution.